The present invention relates to irrigation, and more particularly, to devices for allowing sprinklers to be flushed of debris during their installation.
Residential and commercial irrigation systems typically comprise a series of underground branch lines which are coupled to solenoid actuated diaphragm valves activated by an electronic controller. Sprinklers are connected to the branch lines at regular intervals. In many cases, so-called spray type sprinklers are installed that have a pop-up riser, and a spray nozzle or head with a fixed sector size is screwed over a male threaded outlet at the upper end of the riser.
When a residential or commercial irrigation system is installed, trenches are typically dug into which the branch lines are laid. The branch lines usually consist of a series of horizontal PVC pipe segments coupled with T-shaped connectors that allow sprinklers to be coupled thereto at regular intervals. Sometimes swing arm connectors are used to ensure that tops of the sprinklers end up at the proper grade or level. During this installation process, the sprinkler nozzles can be damaged and therefore they are usually not screwed onto the sprinklers until backfilling of the dirt is completed. Spray type sprinklers are particularly susceptible to fouling by dirt and debris due to the relatively small dimensions of their nozzle openings, e.g. 0.015 inches. In the absence of a nozzle, if the outlet of the sprinkler were left uncovered, backfilled dirt and debris would enter the sprinkler. To avoid this from happening, removable plugs or caps have been developed which temporarily seal the outlet of the sprinkler during installation. These plugs or caps can be readily removed to allow a nozzle to be installed.
Even when plugs or caps are used to seal the outlets of the sprinklers, dirt and debris can still enter the pipes of the system anywhere they are open during the assembly process. Therefore, it is customary to flush the system of all dirt and debris prior to the installation of the nozzles. Where plugs or caps are removed to facilitate flushing, dirt, mud and other debris sometimes re-enter the pipes after flushing and before the nozzles can be installed.
Special flush plugs have therefore been developed for use during sprinkler installation to facilitate flushing without the removal thereof U.S. Pat. No. 5,163,618 of Cordua discloses a flush plug commercialized by HIT that is screwed into the upper end of the riser and uses a vertically reciprocable horizontal sealing plate that selectively seals the entire riser outlet before and after flushing. U.S. Pat. No. 6,045,059 of Weller assigned to the Toro Company discloses a flush plug with a vertical leg that inserts and locks into the upper end of the riser and also relies upon a horizontal circular disc shaped cover to selectively seal the entire riser outlet before and after flushing. Each of the foregoing patented flush plugs disadvantageously relies upon the proper mating of a circular disk like element of the flush plug with the entire circumference of the upper end of the sprinkler riser that defines the outlet.
U.S. Pat. No. Des. 319,489 of Han et al. assigned to Anthony Manufacturing Corporation shows a design for a sprinkler flush plug that is widely commercialized under the RAIN BIRD trademark. It has a gate formed as a three-sided rectangular cut-out region in a top horizontal wall of the plug. This gate deflects to allow water and debris to be flushed out of the sprinkler. However, there is a substantial gap between the gate and the remainder of the wall in which it is formed which can allow dirt and other debris into the sprinkler. In addition the water flushed out of the sprinkler through the deflecting gate of this plug flows more or less around the sprinkler back into the excavation area.